New innovation in microwave technology has lent itself to a wide range of noninvasive measurements. Among the various applications in the medical field is the measurement of cardiac output and other cardiac indices. The technique utilizes a safe, low power electromagnetic energy that is non- ionizing and non fatiguing. Its low cost and simplicity makes it ideal for aiding in the management of congestive heart failure patients, which represent the single most expensive DRG in the USA. A working prototype (called "VSM") incorporating this technology have been used to obtain preliminary qualitative data from animals and humans. These studies demonstrated a direct correlation between the VSM signal and the volumetric changes of the cardiac cycle. The requested funds will extend the animal and in-vitro research to obtain quantitative data and to gain a better understanding of the relationship between the components of the VSM signal and the cardiac cycle. The research will use chronic pig preparations with implanted pressure and flow gages. Cardiac output will manipulated by an implanted inferior vena cava occluder. The VSM signal will be compared against aortic flow measured by an ultrasonic transducer. In-vitro experiments will use an existing test apparatus, representing the chest and heart, to obtain control data. PROPOSED COMMERCIAL APPLICATION: The proposed research will yield a new non-invasive, low cost cardiac output monitor. It's potential application is anywhere where measuring hemodynamic parameters is Important, particularly to help manage congestive heart failure patients.